Buy Gems when you have enough money because you will be able to sell them for great values when you have more than 25, do not upgrade strength until you have completed the "find the archaeologist quest." If you go and try to get the sword outside of the temple then you will only need to upgrade your strength 3 times, at the start of your adult stage. Do not do the killer wasp quest instead go through witchwood and go back to oakvale, you will be able to buy emeralds cheap here.